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Topic: Blue substance  (Read 2273 times)

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Offline WiXoo

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Blue substance
« on: June 20, 2013, 07:39:28 AM »
Hello,

I have a question. I'm doing this reaction, first picture in the attachment. Than I separate the product via filtration. When I analyze filtates via Thin Layer Chromatography I get from the start: orange-red stain which is DADADSK (pic. no. 1)m than something blue (I don't know what this can be) and than orange-violet stain presenting ASK and AHASK (pic. no. 2 a 3).

I need to know what the blue stain is. My personal idea is some complex maybe with copper. But I don't know. Please help me.

Offline Dan

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Re: Blue substance
« Reply #1 on: June 20, 2013, 08:11:51 AM »
Have you attempted to isolate and analyse it? If not, I would try to.
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Offline WiXoo

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Re: Blue substance
« Reply #2 on: June 20, 2013, 08:17:47 AM »
Isolate how?

Offline Dan

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Re: Blue substance
« Reply #3 on: June 20, 2013, 09:10:28 AM »
You have already shown that you can separate it from the other components by chromatography....
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Offline gritch

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Re: Blue substance
« Reply #4 on: June 23, 2013, 05:10:00 PM »
I would definitely say a blue stain is likely a copper complex. If I recall correctly copper sulfates tend to be a nice blue color - it might simply be copper sulfate, which seems a likely by product given your reaction conditions.

I would try taking a small amount of you reaction solution and filtering it through alumina. That should hopefully remove any excess copper. Test it was TLC and see if the blue spot is still there afterwards.

Offline Arkcon

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Re: Blue substance
« Reply #5 on: June 23, 2013, 06:35:15 PM »
I can't be absolutely sure, but I'd bet that straight up copper sulfate on a TLC plate, in the quantities usually left over after a reaction, would be practically invisible. Also note, the blue color appears to be intermediate in polarity, between two other products. You may want to really isolate it in order to understand your reaction better.
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